The immobiliser transponder for the laser keys should be the 'carbon' type that look like a plastic chip rather than the previous glass tube.
Make sure you have the right transponder for the key and you should be ok.
Like you say, if it doesn't work you can always return it.

well as I need a spare cutting anyway, I have had Cube Auto Locksmiths advise that for £140 (surprisingly cheap compared to some!) they will come out and cut / program me a folder remote key for my car, Since I was looking at £130 ish for the normal transponder key and just shy of ten for the ebay (then whatever to cut) I think I will just get the flip done by them, but it looks like it could be a handy little answer to anyone who actually wants to get a flip key for a fraction of the cost!

If anyone does get one, feel free to share the feedback! I might still get one later anyway for my 'spare'

Thats what ive been wanting to do. The main body of the original key looks the same as the one that ive got at the moment but I dont know if the actual key bit is the same :/!it looks flatter on the picture so maybe not the right one for my car?

I've done the conversion from a 3 button to a flip key for both my MK 2 mondeo and my daughters MK 1 Ka, they're a bit fiddly to do, having to hold tension on the sping whilst putting them back together, but the end result is far better than i expected.

heres the end result

Naturally you will have to have the blade cut to suit your car, but all the other gubbins, transponder chip, battery and circuit board will transfer from your standard 3 button remote

Oem stands for original equipment manufacturer, i.e. Original parts and not aftermarket copies.
Regarding the key, like you say, if you break the chip or circuits then it's a real mare, tbh I'd recommend you buy a whole new key and then find an auto locksmith that will cut and code it for you.
I got a spare made up almost as soon as I bought my car, the way I see it is that if you lose/break that new key you still have the original ones to fall back on.

I was lucky with this car, the guy i bought it from had 3 keys for it, so using one of the old remotes from my previous mondeo i made my flip key using the chip, electronics and battery from the old mondeo remote, then once i had the blade cut for this car, I programmed it to start the car using the 2 working key system.

So now i have 4 keys for mine, one flip key, one remote key and 2 standard non-remote keys